Adding data via subqueries. The InsertSelect class
Glossary Item Box
Introduction
The Terrasoft.Core.DB.InsertSelect class is used to build queries for adding records in bpm’online database tables. The Terrasoft.Core.DB.Select class instance is used as the source for adding data (see “Retrieving information from database. The Select class”). As a result of creating and configuring the instance of Terrasoft.Core.DB.InsertSelect, the INSERT INTO SELECT SQL-expression query to the application database will be built.
ATTENTION
When working with the InsertSelect class, the access permissions are not applied to the added records. No application permissions are applied to such records (including object permissions by operation, records or columns). User connection is only used for accessing the database table.
NOTE
After the InsertSelect query is executed, the database will be complemented with all records returned in its Select. subquery.
The “Terrasoft.Core.DB.InsertSelect” class
NOTE
Use the “.NET class libraries of platform core” documentation to access the full list of the InsertSelect class methods and properties, its parent classes and the implemented interfaces.
Constructors
- public InsertSelect(UserConnection userConnection) – creates a class instance with the specified UserConnection.
- public InsertSelect(InsertSelect source) – creates a class instance that is a clone of the instance passed as an argument
Properties.
Table 1. Primary properties of the class
| Property | Type | Description |
|---|---|---|
| UserConnection | Terrasoft.Core.UserConnection | The current user connection at the moment of executing the query |
| Source. | Terrasoft.Core.DB.ModifyQuerySource | Data source |
| Parameters | Terrasoft.Core.DB.QueryParameterCollection | Collection of the query parameters |
| HasParameters | bool | Determines whether the query has any parameters |
| BuildParametersAsValue | bool | Determines whether the query parameters are to be added as values into the query text |
| Columns: | Terrasoft.Core.DB.ModifyQueryColumnValueCollection | Collection of values of the query columns |
| Select. | Terrasoft.Core.DB.Select | The Terrasoft.Core.DB.Select instance used in the query. |
Methods
Table 2. Primary methods of the class
| Methods | Description |
|---|---|
| string GetSqlText() | Returns the SQL text of the current query |
| void BuildSqlText(StringBuilder sb) | Generates the query text via the StringBuilder instance |
| void ResetCachedSqlText() | Clears the cached text of the query |
| QueryParameterCollection GetUsingParameters() | Returns the collection of parameters used by the query |
| void ResetParameters() | Clears the collection of the query parameters |
| void SetParameterValue(string name, object value) |
Sets the value of the query parameter Parameters:
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void InitializeParameters() |
Initiates the collection of the query parameters. |
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int Execute() |
Executes the query. Returns the number of records involved by the query. |
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int Execute(DBExecutor dbExecutor) |
Executes the query using the DBExecutor instance. Returns the number of records involved by the query. |
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InsertSelect Into(string schemaName) InsertSelect Into(ModifyQuerySource source) |
Adds the data source to the current query. Parameters:
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InsertSelect Set(IEnumerable<string> sourceColumnAliases) InsertSelect Set(params string[] sourceColumnAliases) InsertSelect Set(IEnumerable<ModifyQueryColumn> columns) InsertSelect Set(params ModifyQueryColumn[] columns)
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Adds a set of columns to the current query, where the values will be added via the subquery. Returns the current InsertSelect instance. Parameters:
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InsertSelect FromSelect(Select subSelect) InsertSelect FromSelect(Query subSelectQuery) |
Adds the SELECT clause to the current query. Parameters:
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Use cases
You can download the package with the configuration web serice implementing the below described cases using the following link.
Example 1
Receive the SQL-query text.
public string GetSqlTextExample(string contactName, string accountName) { var result = ""; var id = Guid.NewGuid(); var select = new Select(UserConnection) .Column(Column.Const(contactName)) .Column("Id") .From("Account") .Where("Name").IsEqual(Column.Parameter(accountName)) as Select; var insel = new InsertSelect(UserConnection) .Into("Contact") .Set("Name", "AccountId") .FromSelect(select); result = insel.GetSqlText(); return result; }
Example 2
Add the contact with the specified name and account.
public string InsertContactWithAccount(string contactName, string accountName) { contactName = contactName ?? "Unknown contact"; accountName = accountName ?? "Unknown account"; var id = Guid.NewGuid(); var select = new Select(UserConnection) .Column(Column.Const(contactName)) .Column("Id") .From("Account") .Where("Name").IsEqual(Column.Parameter(accountName)) as Select; var insel = new InsertSelect(UserConnection) .Into("Contact") .Set("Name", "AccountId") .FromSelect(select); var affectedRows = insel.Execute(); var result = $"Inserted new contact with name '{contactName}'" + $" and account '{accountName}'." + $" Affected {affectedRows} rows."; return result; }
Example 3
Add the contact with the specified name and connect it to all accounts.
public string InsertAllAccountsContact(string contactName) { contactName = contactName ?? "Unknown contact"; var id = Guid.NewGuid(); var insel = new InsertSelect(UserConnection) .Into("Contact") .Set("Name", "AccountId") .FromSelect( new Select(UserConnection) .Column(Column.Const(contactName)) .Column("Id") .From("Account") as Select); var affectedRows = insel.Execute(); var result = $"Inserted {affectedRows} new contacts with name '{contactName}'"; return result; }
